10GE WAN PHY: Physical Medium Attachment (PMA) IEEE 802.3 Meeting, Albuquerque March 6-10, 2000 Norival Figueira, Paul Bottorff, David Martin, Tim Armstrong, Bijan Raahemi.. Enrique Hernandez-Valencia.. Nevin Jones. Pankaj Kumar. Bjørn Liencres. Tom Palkert. Iain Verigin, Stuart Robinson, Tom Alexander... Nader Vijeh. Frederick Weniger. Nortel Networks Lucent (Bell Labs) Lucent Microelectronics Level One/Intel Juniper Networks AMCC PMC Sierra Lantern Communications Vitesse V1.0
Based on Posted Document Proposal for a 10 Gigabit Ethernet WAN PHY http://grouper.ieee.org/groups/802/3/10g_study/public/ nov99/figueira_2_1199.pdf 10GE WAN PHY: PMA, March 2000-1
Agenda PMA/PMD interface PCS/PMA interface is conceptual PMA frame and overheads PMA framing functions Transmit and Receive PMA frame PMA frame synchronization process x 7 + x 6 +1 frame-synchronous scrambler 10GE WAN PHY: PMA, March 2000-2
Functional Block Diagram 10GMII TXD<31:0> 10GTX_CLK TXC<3:0> Flow control RXD<31:0> RX_CLK RXC<3:0> 312.5 M TXD<31:0>/s PCS TRANSMIT RECEIVE tx_data tx_control rx_data rx_control Conceptual Interface PMA PMD TRANSMIT PMA Frame tx_bit<15:0> RECEIVE PMA Frame rx_bit<15:0> 622.08 M tx_bit<15:0>/s Transmit MDI Receive 10GE WAN PHY: PMA, March 2000-3
Possibly Better Terminology 10GMII TXD<31:0> 10GTX_CLK TXC<3:0> Flow control RXD<31:0> RX_CLK RXC<3:0> 312.5 M TXD<31:0>/s PCS 1 TRANSMIT RECEIVE tx_data tx_control rx_data rx_control Conceptual Interface TRANSMIT PMA Frame PCS 2 PMA/PMD tx_bit<15:0> Transmit MDI RECEIVE PMA Frame Receive rx_bit<15:0> 622.08 M tx_bit<15:0>/s 10GE WAN PHY: PMA, March 2000-4
PMA Interfaces PCS/PMA conceptual interface PMD interface tx_bit<15:0> 16-bit vector representing two octets received from the PMA transitions synchronously with tx_bit_clk tx_bit_clk 622.08 MHz clock generated by the PMA rx_bit<15:0> Most recently received 16 bits (MSB first) from the MDI. It is a continuous and unaligned sequence of octets transitions synchronously with rx_bit_clk rx_bit_clk 622.08 MHz clock generated by the PMD all LVDS 10GE WAN PHY: PMA, March 2000-5
PMA/PMD Interface PMA (Conceptual view) Transmit process Receive process 622.08 MHz Serialized octets (MSB first) Serialized octets (MSB first) 622.08 MHz 15 16-bit word 0 1 1 15 16-bit word 0 tx_bit_clk tx_bit<15:0> rx_bit<15:0> rx_bit_clk Transmit PMD MDI Receive 10GE WAN PHY: PMA, March 2000-6
PMA Framing Functions Transmit PMA Frame PMA framing of octet stream Scrambling of PMA frames using the x 7 +x 6 +1 frame-synchronous scrambler Transmission of resulting data stream to the PMD sublayer depends on the PMD interface 10GE WAN PHY: PMA, March 2000-7
PMA Framing Functions (cont.) Receive PMA Frame Receiving of data stream from PMD sublayer depends on PMD interface PMA frame synchronization and octet delineation Descrambling of PMA frames with the x 7 +x 6 +1 frame-synchronous scrambler 10GE WAN PHY: PMA, March 2000-8
PMA Frame 576 octets PMA Frame = STS-192c Frame 17280 octets 9 rows Section Transport Overhead Line (STS-192c) Envelope Capacity (STS-192c) SPE IDLE packet IDLE Path Overhead column Fixed Stuff Payload Capacity 9 rows IDLE packet PCS data stream 1 63 16640 16704 octets IDLE STS-192c = Synchronous Transport Signal level 192, c = concatenated SPE = Synchronous Payload Envelope 10GE WAN PHY: PMA, March 2000-9
SPE Position 17280 columns Transport Overhead 9 rows pointer Start of SPE SPE 125 µs 9 rows Transport Overhead Path Overhead 10GE WAN PHY: PMA, March 2000-10
Octet Transmission Order Top to bottom, row-by-row, left to right PMA frame 1 Transport Overhead Envelope Capacity 2 10GE WAN PHY: PMA, March 2000-11
Overhead Layers Payload Payload Map payload and Path Overhead into SPE Map SPE and Line Overhead into PMA frame Map Section Overhead into PMA frame Path Line Section PMA Frame PMA Frame 10GE WAN PHY: PMA, March 2000-12
Transport Overhead calculated fixed value provisioned Section Overhead Line Overhead A1 A1 A1 A1 A2 A2 A2 A2 J0 Z0 Z0 B1 H1 H1 H1 H1 H2 H2 H2 H2 H3 H3 H3......... K1 K2 Z0 H3 STS-1# Column# S1.................. 1 2 3 192 1 2 3 192 1 2 3 1 2 3 192 193 194 195 384 385 386 387 576 192 = Undefined overhead octets (set to zero) = Defined overhead octets (B2, E1-2, F1, D1-12, M1, Z1-2), unused by 10GE WAN PHY (set to zero) 10GE WAN PHY: PMA, March 2000-13
Section Overhead: A1 and A2 Framing octets Used by the PMA frame synchronization process to determine where octets and the PMA frame start Transition from A1 to A2 octets is used for synchronization Fixed value: A1 = 11110110 A2 = 00101000 Transition from A1 to A2 A1 A1A2 A2... Transport Overhead PMA frame Envelope Capacity 10GE WAN PHY: PMA, March 2000-14
Section Overhead: J0 and Z0 J0 ( Section Trace ) Allows a receiver to verify its continued connection to the intended transmitter Provisioned Value When no value is provisioned, J0 shall be set to 00000001 Z0 ( Section Growth ) Fixed value: 11001100 10GE WAN PHY: PMA, March 2000-15
Section Overhead: B1 Section BIP-8 Used as a Section error monitoring function 7 6 5 4 B1 3 2 1 0 Calculated value: BIP-8 code (using even parity) over all the bits of the last transmitted PMA frame after scrambling NOTE Even parity over the bit 7 of all the octets of the PMA frame BIP-8 (Bit-Interleaved Parity-8) with even parity: The i th bit of the code provides even parity over the i th bit of all the covered octets. BIP-8of the bit sequence 11110000 00001111 is 11111111. 10GE WAN PHY: PMA, March 2000-16
Line Overhead: H1 and H2 Payload Pointer Allows the SPE to be dynamically aligned within the Envelope Capacity Values: All H1 octets after the first one are set to the fixed value 10010011 All H2 octets after the first one are set to the fixed value 11111111 STS-1# All set to 10010011 All set to 11111111 H1 H1 H1... H1 H2 H2 H2......... 1 2 3 192 1 2 3 H2 192 10GE WAN PHY: PMA, March 2000-17
Line Overhead: H1 and H2 (cont.) First H1 and H2 16-bit word containing an NDF field and a 10-bit STS pointer in the range of 0 to 782 Fixed values: 10GE WAN PHY transmits H1 = 01100010 and H2 = 00001010, i.e., normal STS pointer = 522 Receiver 10GE WAN PHY shall be able to process arbitrary NDF and STS pointer values (which may be changed by a transport network) First H1 First H2 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 NDF NDF (new data flag) field 0110 = normal pointer 1001 = set new pointer 10-bit STS pointer value I D I D I D I D I D I = increment bit, D = decrement bit 10GE WAN PHY: PMA, March 2000-18
Line Overhead: H1/H2 and SPE Position 17280 columns Transport Overhead 192 octets (not to scale) 9 rows H1 H2 H3 10-bit pointer (first H1 and H2) Transport Overhead 0 1 2... 522 523 Start of SPE Path Overhead SPE 782 125 µs 9 rows H1 H2 H3 10GE WAN PHY: PMA, March 2000-19
Line Overhead: H3 Pointer Action Bytes Used for SPE frequency justification Allows LTE to have slightly different clocks at the receiver and transmitter paths Content: Carries 192 extra SPE octets in the event of a negative pointer adjustment, i.e., which may be required when the receiver clock is faster than the transmitter clock Set to zero when not used H1 H2 H3 Transport Overhead PMA frame Envelope Capacity Negative pointer adjustment (additional 192 octets for transmission) 10GE WAN PHY: PMA, March 2000-20
Line Overhead: K1, K2, and S1 K1 and K2 Fixed values: K1 = 00000001, K2 = 00010000 K1 and K2 are used on the protection line for automatic protection switching signaling. Above settings indicate a working channel rather than the protection channel. S1 Fixed value: 00001111 Indicates quality clock information to receiver. Above setting indicates don t use for synchronization 10GE WAN PHY: PMA, March 2000-21
Path Overhead and Fixed Stuff Path Overhead Fixed Stuff 63 columns fixed value calculated Defined overhead octets (F2, H4, Z3-5), unused by 10GE WAN PHY (set to zero) J1 B3 C2 G1... 9 rows Fixed Stuff columns provide compatibility with SONET/SDH byte-interleaving and concatenation rules (set to zero) 10GE WAN PHY: PMA, March 2000-22
Path Overhead: J1, B3, and C2 J1 ( Path Trace ) Fixed value: 00000000 B3 ( Path BIP-8 ) Used as a Path error monitoring function Calculated value: BIP-8 code (using even parity) over all the octets of the last transmitted SPE before (x 7 +x 6 +1) scrambling C2 ( Path Signal Label ) Identifies the contents of the STS SPE (i.e., 10GE WAN PHY) Fixed value: 00011010 (provisional value assigned to 10 GE) 10GE WAN PHY: PMA, March 2000-23
Path Overhead: G1 Path Status Conveys the Path terminating status and performance back to the transmitter (i.e., a PTE) Calculated value: REI-P field = number of bit errors detected with the B3 octet of the last received SPE RDI-P field = Detected defects on the received signal (values are TBD) Propose to support: Loss of Packet Delineation (LPD-P) Loss of Pointer (LOS-P) Payload Mismatch (PLM-P) 7 6 5 4 G1 REI-P = Path Remote Error Indication RDI-P = Path Remote Defect Indication 3 REI-P RDI-P 0 REI-P field 0000 to 1000 = 0 to 8 errors when received, 1xx1 = 0 errors 2 1 0 10GE WAN PHY: PMA, March 2000-24
Reference Diagram: Transmit PMA Frame PMA Service Interface tx_control tx_data Functional View Transmit PMA Frame Flow Control B1 (BIP-8) Path Overhead Fixed stuff for next SPE B3 (BIP-8) Line Overhead Section Overhead Inhibit scrambling first row of Section OH for next frame + + + SPE x 7 +x 6 +1 scrambler From Receive process (for G1) PMA frame formation (stages) (1) Path Overhead and fixed stuff columns (2) Line Overhead (3) Section Overhead (4) Scramble with x 7 +x 6 +1 (first row of Section Overhead, i.e., A1/A2, J0, and Z0, is not scrambled) (5) 16-bit words are transmitted to PMD (depends on PMD interface) 1 tx_bit_clk 16-bit word assembly tx_bit<15:0> PMD Service Interface 10GE WAN PHY: PMA, March 2000-25
Reference Diagram: Receive PMA Frame Functional View PMA frame processing (stages) (1) Serialize received PMD signal (2) PMA frame synchronization and octet delineation (3) Descramble with x 7 +x 6 +1 (first row of Section Overhead is not descrambled) (4) Extract Section Overhead, Line Overhead, Path Overhead, Fixed Stuff columns (5) Remaining octets = payload To Transmit process (for G1) PMA Service Interface rx_data - x 7 +x 6 +1 Descrambler PMA frame Synchronization 1 Serializer rx_control Flow Control Section Overhead Line Overhead Path Overhead Fixed stuff Columns inhibit descrambling of first row of Section Overhead Look for A1/A2 transition Receive PMA Frame rx_bit<15:0> 1 rx_bit_clk PMD Service Interface 10GE WAN PHY: PMA, March 2000-26
Reference Diagram tx_control Transmit PMA Frame Flow Control PMA Service Interface B1 (BIP-8) 1 tx_bit_clk Path Overhead Fixed stuff for next SPE B3 (BIP-8) Line Overhead Section Overhead Inhibit scrambling first row of Section OH for next frame PMD Service Interface tx_data + + + SPE x 7 +x 6 +1 scrambler 16-bit word assembly tx_bit<15:0> Conceptual Interface Information required to calculate G1 622.08 Mbaud PMA Service Interface rx_data - x 7 +x 6 +1 Descrambler PMA frame Synchronization 1 rx_bit<15:0> Serializer rx_control Flow Control Section Overhead Line Overhead Path Overhead Fixed stuff Columns inhibit descrambling of first row of Section Overhead Look for A1/A2 transition 1 rx_bit_clk PMD Service Interface Receive PMA Frame 10GE WAN PHY: PMA, March 2000-27
PMA Frame Synchronization Uses A1/A2 transition (i.e., frame marker) for frame and octet delineation Looks for the A1/A2 framing pattern consistently Expects it to appear once every 155520 octets (155520 = length of the PMA frame) When the framing pattern appears in the right place enough times, correct frame synchronization is assumed A1/A2 transition (frame marker) not scrambled A1 A1 A2 A2 J0Z0 Z0 Transport Overhead Envelope Capacity 10GE WAN PHY: PMA, March 2000-28
PMA Frame Synchronization (cont.) Posted document Provides a set of rules to be satisfied by a PMA frame synchronization process Does not provide specific details on how a PMA frame synchronization process works Does not imply any specific implementation. Any PMA frame sync procedure that complies with the defined set of rules is acceptable This presentation shows the state diagram of a frame synchronization processes similar to the ones used in typical OC-192 equipment 10GE WAN PHY: PMA, March 2000-29
PMA Frame Sync: START State begin Initial state Searches bit by bit for i correct A1 octets Moves to A1_ALIGN state on an exact match i correct A1s START [bit by bit] A1_ALIGN [octet by octet] Did not find i correct A1s 10GE WAN PHY: PMA, March 2000-30
PMA Frame Sync: A1_ALIGN State begin Confirms byte alignment Moves to PRESYNC state on at least j correct A1 octets followed by k correct A2 octets Moves to START state if pattern is not found i correct A1s START [bit by bit] A1_ALIGN [octet by octet] Did not find i correct A1s PRESYNC [octet by octet] j correct A1s followed by k correct A2s Pattern not found 10GE WAN PHY: PMA, March 2000-31
PMA Frame Sync: PRESYNC State begin SYNC [frame by frame] PRESYNC [octet by octet] i correct A1s START [bit by bit] A1_ALIGN Did not find i correct A1s Checks frame for correct A1/A2 transition pattern at correct place Moves to SYNC state on n correct A1/A2 [octet transition by octet] patterns Moves to START state on an incorrect A1/A2 transition pattern j correct A1s followed by k correct A2s Pattern not found n correct A1/A2 transition patterns Incorrect A1/A2 transition pattern 10GE WAN PHY: PMA, March 2000-32
PMA Frame Sync: SYNC State begin SYNC [frame by frame] START [bit by bit] Correct A1/A2 transition pattern or < m consecutive incorrect transitions m consecutive incorrect A1/A2 transition patterns PRESYNC [octet by octet] i correct A1s j correct A1s followed by k correct A2s Did not find i correct A1s Checks frame for A1/A2 transition A1_ALIGN pattern at correct place [octet by octet] Moves to START state with m consecutive Pattern frames not found with incorrect A1/A2 transition patterns n correct A1/A2 transition patterns Incorrect A1/A2 transition pattern 10GE WAN PHY: PMA, March 2000-33
PMA Frame Sync: State Diagram begin SYNC [frame by frame] Correct A1/A2 transition pattern or < m consecutive incorrect transitions m consecutive incorrect A1/A2 transition patterns i correct A1s START [bit by bit] A1_ALIGN [octet by octet] Did not find i correct A1s PRESYNC [octet by octet] j correct A1s followed by k correct A2s Pattern not found n correct A1/A2 transition patterns Incorrect A1/A2 transition pattern 10GE WAN PHY: PMA, March 2000-34
PMA Frame Sync. Performance Example for m = 4, A1/A2 transition pattern = 2 A1/A2s Probability of frame loss 1.049 10 6 BER 4 = 1.049 10-42 (@ BER = 10-12 ) Average interval to frame loss 3.7 x 10 30 years (@ BER = 10-12 ) (> estimated age of observable universe, i.e., ~ 10 10 years) More robust implementations are possible, e.g., see 10GE WAN PHY Delineation Performance http://grouper.ieee.org/groups/802/3/10g_study/public/ email_attach/delineation_perf.doc 10GE WAN PHY: PMA, March 2000-35
x 7 +x 6 +1 Frame-Synchronous Scrambler Purpose Assures that the optical interface signal has an adequate number of transitions for line rate clock recovery at the receiver Scrambles All the octets of the PMA frame with the exception of the first row of the transport overhead State is periodically resynchronized Scrambler state is reset to 1111111 on the most-significant bit of the octet following the last Z0 octet 10GE WAN PHY: PMA, March 2000-36
Use of x 7 +x 6 +1 Scrambler Reset scrambler state to 1111111 A1 A1A2 A2J0Z0 Z0 Transport Overhead Envelope Capacity PMA frame Scrambled Not scrambled 10GE WAN PHY: PMA, March 2000-37
x 7 +x 6 +1 Scrambler/Descrambler (Functional Diagram) Scrambled/ descrambled bit stream XOR 7-bit shift register D Q D Q D Q D Q D Q D Q D Q C S C S C S C S C S C S C S XOR Clock Reset to 1111111 Descrambled/ scrambled bit stream Scrambler/descrambler state = content of the 7-bit shift register 10GE WAN PHY: PMA, March 2000-38
Bit Order of Scrambling/Descrambling Most significant bit (LSB) first Octets 7 6 5 4 3 2 1 0 1 x 7 + x 6 + 1 Scrambler/Descrambler 7 6 5 4 3 2 1 0 1 Octets (Functional diagram) 10GE WAN PHY: PMA, March 2000-39
Summary PMA/PMD interface 16-bit LVDS PMA frame and overheads Described proposed minimum set of overheads PMA framing functions Described Transmit and Receive PMA frame processes PMA frame synchronization process Described a typical frame synchronization process x 7 + x 6 +1 frame-synchronous scrambler Described functional diagram and resynchronization scheme 10GE WAN PHY: PMA, March 2000-40